1. Field of the Invention
The present invention is generally related to a lubrication system for a marine engine and, more particularly, to a lubrication system which displaces the axis of rotation of the oil pump rotor from the axis of rotation of an output shaft of the engine which drives the oil pump.
2. Description of the Prior Art
Many different types of lubrication systems are well known for use in conjunction with four cycle engines. In addition, several types of oil pump configurations and locations in association with engines are known to those skilled in the art.
U.S. Pat. No. 6,192,853, which issued to Natsume on Feb. 27, 2001, describes an oil pump for a four cycle outboard motor. The outboard motor oil pump driving arrangement is disclosed wherein the oil pump is driven by a spline connection position between the engine crankshaft and the driveshaft. There is a spline connection also between the crankshaft and the driveshaft and this spline connection is axial spaced from the spline connection to the pump drive element with the splines being spaced from each other by a non-spline section so as to reduce stress risers and to make assembly and disassembly easy even if the parts are deformed.
U.S. Pat. No. 5,975,970, which issued to Daikoku on Nov. 2, 1999, describes an oil pump unit for an outboard motor. The outboard motor comprises an engine holder arranged to be mounted to a hull, an engine disposed in an upper portion of the engine holder in a mounted state thereof, an oil pan disposed in a lower portion of the engine holder, a crankshaft vertically disposed in the engine, a cam shaft disposed to extend in parallel to the crankshaft, and a lubricating device including an oil pump unit disposed to a lower surface of the engine holder and adapted to circulate an oil in the engine. The oil pump unit comprises a pump case having a case body to be mounted to the engine holder, a pump driveshaft operatively connected to the cam shaft for operating the oil pump disposed on the lower surface of the engine holder, and suction and discharge ports. The pump driveshaft is detachably connected to the cam shaft to be slidable in a vertical direction in the mounted state, and the suction port and the discharge port operatively communicate with the suction and discharge ports of the engine, respectively.
U.S. Pat. No. 6,189,501, which issued to Fujii et al on Feb. 20, 2001, describes a lubricating apparatus for an engine. The lubricating apparatus of an outboard motor comprises an oil pan disposed in a lower portion of an engine and providing with an oil accumulating tank, an oil strainer for straining an oil accumulated in the oil accumulating tank, an oil pump for supplying strained oil to an inside portion of the engine, the oil strainer and the oil pump being mounted to a structural member such as a pump case disposed above the oil pan so as to be connected to each other, and an oil suction pipe extending from the oil strainer to a bottom portion of the oil accumulating tank.
U.S. Pat. No. 5,778,847, which issued to Takahashi et al on Jul. 14, 1998, describes a four cycle outboard motor. The outboard motor has a high performance V-type twin overhead cam four cycle internal combustion engine. The oil reservoir for the engine is disposed in a driveshaft housing below the engine and an oil pump is driven off the lower end of the engine crankshaft for circulating the oil from the oil tank to the engine. The oil supply system for the engine includes a vertically extending main gallery and a drain passage which extends in parallel side-by-side relationship and which are disposed over the oil tank for ease of oil return. The exhaust and cooling system for the engine is configured so as to minimize heat transfer between the exhaust system and the lubricating system and to maintain a compact assembly.
U.S. Pat. No. 6,041,892, which issued to Watanabe et al on Mar. 28, 2000, describes an oil pump for an outboard motor. The oil pump for a lubricating system of an outboard motor is disclosed. The motor has a cowling defining an engine compartment, a water propulsion device, and a guide member having an upper surface and a lower surface, the guide member positioned in the cowling and generally dividing the engine compartment into an upper part and a lower part. An engine is positioned in the upper part of the engine compartment within the cowling and has an output shaft arranged to drive the water propulsion device. The lubricating system includes an oil pan positioned below the guide member and an oil passage leading from the pan through the guide member. The oil pump is positioned in the upper part of the engine compartment, but below the engine, and is driven by a lower end of the output shaft of the engine which extends below the engine, the oil pump having an oil inlet in communication with the oil passage through the guide member.
U.S. Pat. No. 5,876,188, which issued to Okamoto on Mar. 2, 1999, describes an oil pump arrangement for a four cycle outboard motor. The oil pump for an engine of an outboard motor of the type including a block with an output shaft extending therefore is disclosed. The oil pump includes an oil pan comprising an outer housing defining an oil chamber and a pumping chamber therein. The oil pump includes a pumping mechanism for pumping oil from the oil chamber to the engine. The pumping mechanism is positioned within the pumping chamber, with the outer housing defining the pumping chamber acting as a pump housing therefore. The pumping mechanism is positioned on and driven by the output shaft of the engine which extends through the oil and pumping chambers of the oil pan. A recess in the pumping chamber accommodates a flywheel, which is also positioned on and driven by the output shaft of the engine.
U.S. Pat. No. 5,870,991, which issued to Mineno on Feb. 16, 1999, describes a lubricating device for an outboard motor. The outboard motor comprises an engine of a vertical type in which a crankshaft is disposed vertically in an installed state of the engine, an engine holder support the engine, an oil pan which is disposed below the engine through the engine holder and in which an oil is accumulated, and a lubricating device for lubricating the oil from the oil pan to an inside of the engine. The lubricating device comprises an oil pump mounted to a lower side portion of the engine holder and adapted to suck the oil accumulated in the oil pan, an oil suction passage and an oil discharge passage. The oil suction passage and oil discharge passage extend in parallel to each other from the oil pump and are formed integrally with the inside portion of the engine holder.
U.S. Pat. No. 5,778,848, which issued to Takahashi et al on Jul. 14, 1998, describes a four cycle outboard motor lubricating system. A four cycle outboard motor has an oil tank that is disposed at least in part in the driveshaft housing of the outboard motor and an oil pump that is driven off of the lower end of the crankshaft. At least a portion of the conduits for transmitting oil from the oil tank to the oil pump and from the oil pump to the engine for its lubrication are formed integrally in a lower face of the cylinder block.
U.S. Pat. No. 5,704,819, which issued to Isogawa on Jan. 6, 1998, describes an oil pan arrangement for a four cycle outboard motor. The outboard motor has a high performance V-type overhead cam four cycle internal combustion engine. The oil reservoir for the engine is disposed in a driveshaft housing below the engine and an oil pump is driven off the lower end of the engine crankshaft for circulating the oil from the oil tank to the engine. The oil supply system for the engine includes a vertically extending main gallery and a drain passage which extend in parallel side-by-side relationship and which are disposed over the oil tank for ease of oil return. The exhaust and cooling system for the engine is configured so as to minimize heat transfer between the exhaust system and the lubricating system and to maintain a compact assembly.
U.S. Pat. No. 5,687,686, which issued to Takahashi on Nov. 18, 1997, describes a lubricating system for a four cycle outboard motor. The outboard motor embodies an improved lubricating system. The lubricating system drains oil from the cylinder head back to the oil tank, in a manner so as to not add to the length of the engine. In addition, an improved crankcase ventilating system is employed that incorporates a simple baffle arrangement for ensuring that oil thrown by the crankshaft rotation will not pass through the ventilating passage into the cylinder head or escape from the ventilating system.
U.S. Pat. No. 5,524,581, which issued to Rush et al on Jun. 11, 1996, describes an outboard motor with an improved engine lubrication system. The internal combustion engine comprises a cylinder block which defines a cylinder, a crankshaft bearing supported at least in part by the cylinder block, a crankshaft which is rotatably supported by the crankshaft bearing, a piston slidably housed in the cylinder, a connecting rod having one end connected to the piston and an opposite end connected to the crankshaft, a cylinder head mounted on the cylinder block, a camshaft at least partially supported by the cylinder head for rotation relative thereto, an oil pump having an outlet, a first oil conduit communicating between the oil pump outlet and the crankshaft bearing, an oil filter communicating with the first oil conduit for filtering oil only in the first oil conduit, and a second oil conduit communicating between the oil pump outlet and the camshaft. Oil in the second oil conduit is unfiltered between the pump outlet and the camshaft,
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Marine engines known to those skilled in the art typically drive an oil pump with an output shaft of the engine. The axis of rotation of the oil pump rotor is generally coaxial with the axis of rotation of the engine""s output shaft used to drive the pump. Certain known arrangements for lubricating marine engines attach the oil pump rotor to the driveshaft of an outboard motor and connect the driveshaft in torque transmitting relation with the crankshaft of the engine. These known arrangements present certain difficulties in manufacturing, assembly, and maintenance. In addition, these known arrangements of oil pump configurations also present problems relating to sealing the various moving components to prevent water from leaking into oil reservoir compartments. It would therefore be beneficial if an oil lubricating system for a marine engine could be provided which improves the operation of the oil pump by placing it close to the oil reservoir, by providing a marine engine lubricating system that is more easily assembled and repaired, and by making the operation of the oil pump independent from the driveshaft of the outboard motor.
A lubricating system made in accordance with the preferred embodiment of the present invention comprises an oil pump having an inlet port and an outlet port. The oil pump has a rotor supported for rotation about a first vertical axis and the outlet port is connected in fluid communication with at least one lubricating conduit of an engine. An oil reservoir is connected in fluid communication with the inlet port of the oil pump.
An output shaft of the engine is supported by the engine for rotation about a second vertical axis and connected in torque transmitting relation with the rotor of the oil pump. The first and second vertical axes are displaced from each other by a preselected distance and a sleeve is supported for rotation about the second axis. The sleeve is connected in torque transferring relation between the output shaft of the engine and the rotor of the oil pump.
A first torque transferring protrusion is attached to the output shaft of the engine and extends in a direction generally parallel to the second axis. A second torque transferring protrusion is attached to the sleeve, whereby rotation of the first torque transferring protrusion about the second axis causes the first torque transferring protrusion to exert a force against the second torque transferring protrusion. This force causes the sleeve to rotate about the second axis. The first and second torque transferring protrusions can comprise, respectively, first and second pairs of pins.
The lubricating system of the present invention can further comprise a first chain sprocket attached to the sleeve for rotation about the second axis and a second chain sprocket attached to the rotor of the oil pump for rotation about the first axis. A chain is attached to the first and second chain sprockets for transferring torque from the sleeve to the rotor of the oil pump.
The output shaft can be a crankshaft of the engine. A driveshaft is connected in torque transferring relation with the output shaft for rotation about the second axis and the driveshaft can extend through an opening in the sleeve. The oil pump is preferably attached to an adapter plate of the outboard motor and the sleeve is supported by the adapter plate for rotation about the second axis.